Have you ever read a book that kept you hooked, but then came to an ending that was either so outlandish, or so unfulfilling, that it pretty much ruined the book for you? If you have, you know how important endings are.

Even well-known, longtime authors can anger their readers with an ending. Dana Stabenow has enraged loyal readers with a cliffhanger ending in her most recent book, Bad Blood. So much so that Stabenow had to tell readers, in her blog: “In the end, you could trust me to know what I’m doing.” (Personally, I like Stabenow because she never plays it safe in the series, so I’m waiting to see what she does next.)

Gillian Flynn’s blockbuster mystery, Gone Girl, is another one with a controversial ending. No spoilers here, but Flynn said in an interview that she likes endings with “unease.” Of Gone Girl, she said “It was the only thing that made sense to me, that made sense to what was true to the book and true to the characters.”

There’s not many rules for endings, although there do seem to be five types, according to Revision & Self-Editing by James Scott Bell. They are:

1) The happy ending, with the Lead gaining his objective;

2) The unhappy ending, with the Lead losing his objective;

3) The classic tragedy, where the Lead gains his objective but loses something more valuable;

4) The Lead sacrifices his objective for a greater good;

5) The ambiguous or bittersweet ending.

One of my favorite gothic novels, Rebecca by Daphne du Maurier, opens with the now-famous line: “Last night I dreamt I went to Manderley again,” going on to describe the drive into the mansion’s grounds. It ends with a few lines that mirror that opening: “The road to Manderley lay ahead. There was no moon. The sky above our heads was inky black. But the sky on the horizon was not dark at all. It was shot with crimson, like a splash of blood. And the ashes blew towards us with the salt wind from the sea.” It’s a perfect ending, tying together all that came before it.

With crime fiction, the whodunit, or the resolution, is often reached before the very last pages. Those last pages serve as a wrap-up, tying all the loose ends. Here, the writer has the chance to put all straight in the world again.

It’s more delicious, however, when an author leaves something dangling for the next book in a series. Elly Griffiths, who writes atmospheric novels about a forensics archaeologist who helps police, spends much time developing her characters and giving them full-rounded lives. There’s a secret we’ve been privy to, as readers, that affects two families. So, it’s especially interesting when, at the end of House on Seas End, one of the characters is suddenly hit with a realization.

The very last line is: “And, all afternoon, through the lunch and the speeches and the general outpouring of goodwill, Ruth sees Michelle’s face and its slowly dawning suspicion.”

There will be consequences, but not till the next book. With that last line, the author has guaranteed readers will return.